Electric discharge device



May 27, 1930. H. c. RENTSCHLER ELECTRIC DISCHARGE DEVICE Filed Oct. 2,1925 FIGQI FIG INVENTOR 'HARVEY C. RENTSCHL R BY ATTORNEY Patented May27, 1930 UNITED STATES PATENT OFFICE CLAYTON RENTSCHLER, OF EAST ORANGE,NEW JERSEY, ASSIGNOB TO WEBT- INGHOU'SE LAMP COMPANY, A CORPORATION OFPENNSYLVANIA ELECTRIC DISCHARGE DEVICE Application filed October 2,1925. Serial No. 59,986.

This invention relates to electric discharge devices and moreparticularly to glow discharge devices in which the discharge takesplace in a rarefied gaseous atmosphere. The invention is especiallyconcerned with the production of a discharge device utilizing amonatomic gas in which the starting voltage and the operating dischargevoltage fall Within rather narrow and predetermined values and in whichthese voltages remain fixed within these narrow limits over a longperiod of time.

Such devices may be used for controlling or regulating the plate voltagein radio C11- 15 cuits when the plate voltage is obtained from rectifiedalternating current, throughthe use of the so-called B-batteryeliminators. Another use for this type of a device is in a glow.discharge point-to-plate rectifier uslng an inert gas. Still anotherapplication of the device is in connection with protective devices, suchas overload circuit breakers or the like. For all these purposes it isessential that the discharge start at a potential falling withinrelatively narrow limits and that the operating voltage is fairlydefinitely fixed within definite limits.

One of the objects of the invention is to provide a discharge devicewhich will have a low starting potential and operating potential andwhich will be simple and rugged in construction.

Another object of the invention is to provide a gaseous discharge deviceof this nature I 3.6 which will be uniform and dependable in operation.

Another object is to provide a discharge device in which both the breakdown or starting volt-age and the operation voltage fall within 4definite and relatively narrow limits.

Other objects and advantages will hereinafter appear.

I have found that when the anode of a point-to-plate discharge device,utilizing an 4 atmosphere of a monatomic gas, such as used for argon, ora mixture of monatomic gases, consists of mischmetal or a metal of thecerium group of rare earths, that the seasoning of the discharge devicecan be accomplished very simply and that a low starti g and operatingpotential may be obtained. Both of these potentials, moreover, will fallwithin definite limits and the device will operate continuously anduniformly within these limits over a long period of time. The mischmetal appears to serve a double purpose. Residual impurities in the gaswhich come from the elements of the tube, such as insuflicie'ntlytreated electrodes or which exist in the gas as impurities, will becleaned up by the misch metal during the seasoning process. Also, duringthe operation of the tube, the impurities which may be liberated fromthe parts of the tube will be cleaned up and thus the operatingcharacteristics of the device maintained uniform during the lifethereof. At the same time some t of the misch metal will be volatilized-and condensed on the plate, thus giving a lower starting and o eratingpotential than would be obtained if the metal of the plate were composedsolely of one of the common metals purposes of this kind, such asnickel, iron, etc.

In order that this invention may be more fully understood, referencewill be had to the accompanying drawing in which,

Fig. 1 illustrates a discharge device partly in dsection embodying thepresent invention; an v Fig. 2 illustrates, diagrammatically, the methodof utilizing the device for regulating the voltage.

The device comprises an envelope 1 containing a cathode 2, an anode 3and a filling of a monatomic gas or mixture of such gases.

The anode 3 consists of a Wire 4 of nickel or other suitable materialsealed' through the press 5 of the device and has'a strip of misch metal6 clamped or otherwise suitably secured to the outer end thereof,although if desired,

the electrode may be composed entirely of misch metal.

The cathode 2 consists of a cylindrical plate concentric with the anodeand supported from the press 5 by support wires 7 and 8. The cathode maybe composed of nickel, 1ron, molybdenum or any other suitable metal.

The anode and cathode are provided with current conducting leads 9 and10 joined to the wire 4 and the cathode support 7, respectively, and tothe terminals 11 and 12 of the base 13.

To assist in starting the discharge, a pro ection in the form of a wire14. extends from the cathode 2 into close proximity to the anode 3.

The envelope is preferably filled wltlrargon at a pressure of from about3 to 7 m1lh meters of mercury, although other monatomic gases ormixtures of gases may be employed depending on the starting andoperating potentials desired. After filling with gas and sealing off, itis necessary to subject the device to a treating schedule to develop thestarting and operating characteristic thereof. Preferably, suchtreatment consists in operating the device on 220 volt alternatingcurrent with a protective resistance in series therewith for a shorttime and then seasoning the device at 110 volts alternating current forseveral hours. I

This treatment ionizes the gas and heats the anode to a sufficientlyhigh temperature to render the misch metal active so that it iseffective to thoroughly purify the gaseous filling. It also appears torender the cathode more sensitive or active and thus effective toinitiate a discharge therethrough at a relatively low potential. Itappears that a small proportion of the misch metal or some constituentthereof is sputtered, vaporized or otherwise deposited on the cathodefrom the anode. However, I do not desire to be limited by any particulartheory.

Devices so produced have a starting potential of from about 100 to 125volts and a minimum operating potential of about 80 to 100 voltsdepending somewhat upon the gas content. its pressure, the current drawnby the device, etc.

It is obvious that other treatments may be devised for developing thestarting and operating characteristics of the device and that theinvention is not limited to the particular treatment specified.

The misch metal serves throughout the life of the tube to maintain thegas in a pure condition. and the operating and starting characteristicsuniform.

In some instances it may be desirable to use misch metal on the cathodeas a getter in addition to its use on the anode. This would beparticularly helpful if the gas used were not previously purified to afairly high degree. If used on the cathode, the misch metal could bevaporized by high frequency induction or in any other suitable manner toclean up any impurities or common gases re- .purpose such as theoperation of the radio tubes or other device 19. The voltage regulator20 is placed across the line to maintain the voltage constantirrespective of fluctuations in the voltage of the alternating currentsource or of the number of devices in operation. A resistance 21 isprovided for limiting the current to the desired maximum value. Asuitable resistance 22 may be provided to enable current of differentvoltages to be utilized.

Preferably, the resistance 21 is so regulated as to permit a currentflow of approximately 50 milliamperes through the regulator at about 90volts when the switch 23 is closed and the load 19 disconnected. Thiscurrent is sufficient to supply the plate current of radio receivingapparatus having a relatively large number of amplifying tubes. When thetubes or other device 19 are brought into operation, so as to drawcurrent from the rectifier, the regulator, maintains the voltageuniformly at the desired voltage. i. e., about 90 volts. Should thevoltage fall below the minimum operating potential of the regulator, itceases to operate and the full rectified current is available for thedevices 19. Immediately. however, the voltage increases to the startingpotential of the regulator, it again comes into operation. It isessential. therefore, in order to insure a restarting of the regulator,that its starting potential be relatively low and close to its operatingpotentlal. The starting and operating potentials of the describedembodiment of this invention renders it particularly efiicacious forthis purpose.

It is obvious that the invention is susceptible of many embodiments andthat various .a small anode therein and a relatively large cathode, saidanode being formed in part at least of misch metal whereby a low voltagedischarge through said device may be obtained.

3. An electrical discharge device comprising an envelope containing amonatomic gas, electrodes therein operable in the absence of thermionicactivity and'a quantity of misch metal within said envelope forpurifying said gas and reducing the starting and operating potentialsthereof.

4. An electrical discharge device of the point-to-plate type comprisingan envelope containing a rare gas, a small anode and a relatively largecathode therein and a metal of the cerium group of rare earth metalsdisto heat said anode to activate the cerium HARVEY CLAYTONRENTSClll-ER.

posed on one of said electrodes adapted to purify said gas and reducethe starting and operating potentials of the device.

5. A glow discharge device comprising an envelope, a filling ofmonatomic gas therein at a relativelylow pressure, and a plurality ofelectrodes within said envelope'operable in the absence of thermionicactivity, one of said electrodes being composed chiefly of misch metal,whereby said device has a low starting and operating potential.

6. An electrical discharge device of the point-to-plate type comprisingan envelope containing a rare gas, an anode and a cathode,

said cathode having a metal of thevcerium group of rare earth metalsdisposed thereon.

7. An electrical discharge device comprising an envelope containing afilling of argon gas, an anode and cathode within said envelope, saidanode being formed in part, at least, of misch metal and said cathodecontaining a quantity of misch metal on the surface thereof.

8. An alternating current rectifier having a low starting and operatingpotential comprising an envelope containing argon, a relatively largecathode and a small anode therein, one of said electrodes having theuantity of misch metal thereon adapted to re uce the starting andoperating potentials of the device and maintain such potential uniformthroughout the life of the device.

9. The method of reducing the starting and operating potential of agaseous discharge device containing a plurality of electrodes whichconsists in introducing a mutity of misch metal therein on one o theelectrodes, passing a discharge through the device at a potential ofapproximately 220 volts to activate the misch metal and subsequentlyreducing the voltage and continuing the discharge to season the-device.

10. The method of reducing the starting potential of a. point-to-platerectifier of the gaseous discharge t pe comprising forming the anode ofsaid evice of a metal of the cerium group of rare earth metals andsubjecting said device to a discharge sufiicient

